This invention relates to biodevices and contact part structures of biodevices. A so-called enzyme sensor having a specified kind of enzyme attached to the surface of an electrode is used for measuring the concentration of sugar, amino acids, etc. in an organism. Such an sensor is used for making use of the characteristic of the enzyme attached to the electrode for singularly oxidizing or reducing sugar and amino acids to generate molecules and ions, and the concentration of sugar, amino acids, etc. can be measured by detecting the quantity of the generated molecules and ions as the value of the current that flows in the electrode. If the kind of the enzyme attached to the surface of the electrode is changed, furthermore, the type of the substance to be measured can be changed.
This invention relates to biosensors that are usable for measuring the concentration, etc. of such substances in an organism, biodevices that are usable for such biosensors, and contact part structures of such biodevices.
Glucose sensors for measuring the glucose concentration in an organism are being developed as an example of conventionally used enzyme sensor (as disclosed in Japanese Patent Publication Tokkai 5-60722; and W. Kenneth Ward, Lawrence B, Jansen, Ellen Anderson, Gerard Reach, Jean-Claude Klein, and George S. Wilson, “A new amperometric glucose microsensor: in vitro and short-term in vitro evaluation”, Biosensors & Bioelectronics 17, 2002, p. 181-189).
Since these devices have an electrode exposed to the surface and enzyme, etc. are attached to this electrode, one cannot deny the possibility of the enzyme becoming displaced or the sensing parts becoming damaged as the device is inserted into an organism.
As an example of device having an electrode that is not exposed externally, a probe having an indentation formed at the end is being developed (Japanese Patent Publication Tokkai 11-347019). This probe is for examining blood or body fluid taken from an organism and is structured such that an electrode and a reagent to be used for detection of the object under test are disposed inside the indentation. It is documented that the quantity of the blood to be examined can be maintained constant by the volume of the indentation as the examination is carried out with a body fluid contained inside the indentation of the probe.
In recent years, biosensors to be used by penetrating or placing inside an organism are being required, and such biosensors are required to be able to carry out measurements accurately for a long period of time. In order to improve the sensitivity of a biosensor, it is necessary to make the area of its electrode (and in particular its working electrode) large and it is necessary to be able to hold a large amount of enzyme for a long time of use.
Since the probe according to aforementioned Japanese Patent Publication Tokkai 11-347019 uses the end of a working electrode lead at the center of the probe as its working electrode, it is necessary to make the working electrode lead thick in order to make the area of the electrode large. Since the probe itself will become thick if the working electrode lead is made thick, however, the damage to the organism also becomes large when it is used to penetrate it or place inside.
Moreover, since this probe has its hollow section formed in a semispherical shape, the radius of this hollow section must be increased if it is desired to hold a large quantity of enzyme. In such a situation, the probe itself must also be made thick.
Accordingly, this probe can be used for detecting an object under test inside a target object taken or separated from an organism but is not suitable for a device for directly detecting and measuring inside an organism without collecting any object under test inside the organism.
Although it would be very useful if it were possible to combine a biosensor in a treatment using an endoscope or a catheter used by inserting into an organism, such a biosensor allowing to be effectively combined to an endoscope or a catheter has not been developed and its development is being wished for.